1. Field of the Invention
The invention relates to a device for opening and closing a sliding door, in particular for vehicles.
Sliding doors are provided in particular in vehicles in which access to the interior of the vehicle is provided from the side, for example in minibuses or transport vehicles. Such a sliding door is generally constructed in such a way that in the closed or locked position it terminates flush with the surrounding vehicle body and in the opened state, being offset parallel to the side, is movable along the body in at least one guide rail.
In recent times there has been a growing need to be able to move and close such a sliding door automatically, in particular for certain end uses, for example for taxis, freight vehicles, ambulances or the like.
2. Description of the Prior Art
DE-A-38 31 698 discloses a device for opening and closing a sliding door, in particular for vehicles, which closes an aperture in a side. The device possesses a linear drive constructed as a taut chain with a pinion engaging therein provided with an electric motor for displacing the sliding door parallel to the side of the vehicle as well as for swinging out a mounting supporting the sliding door. In addition a guide device consisting of a guide rail fastened to the sliding door as well as guide rollers fastened to the mounting for guiding the sliding door substantially parallel to the side are provided. The linearly constructed driven member of the linear drive, that is the taut chain, is installed in fixed manner on the sliding door. The mounting is supported via a support arrangement which is connected to the side wall and constructed as a guide parallelogram. The pivot levers of the guide parallelogram are mounted in articulated manner on the one hand on the side wall and on the other hand on the mounting with vertical axes of rotation in each case so that they can exercise a support function for the sliding door. At the same time the drive motor is rigidly attached to one of the pivot levers belonging to the guide parallelogram which convert a movement of the mounting of the sliding door substantially perpendicular to the wall into a pivot movement.
This device according to the state of the art has the disadvantage that extensive measures are necessary on the vehicle chassis in order to attach a guide parallelogram which can swing out and support the sliding door. This is greatly disadvantageous in particular when retrofitting the device for opening and closing the sliding door. It is, furthermore, disadvantageous that despite the automatic closing process the actual locking does not ensue automatically. This can represent a safety risk.
WO 93/17211 discloses a device for opening and closing a horizontally displaceable vehicle door having an endless screw connected to the body. The endless screw is accommodated in a rail. Arranged on the screw is a carriage which is movable in translational manner in the rail, the endless screw being driven by a motor. The carriage is connected to the door via a damped connecting rod which preferably assumes an angle of less than 25.degree. to the endless screw. Furthermore, in the door a locking or unlocking device is provided, the locking or unlocking being carried out via an electromagnet.